1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and more particularly, to a method of manufacturing an array substrate for the liquid crystal display device.
2. Discussion of the Related Art
In general, a liquid crystal display (LCD) device includes two substrates, which are spaced apart and facing each other, and a liquid crystal layer interposed between the two substrates. Each of the substrates includes electrodes. The electrodes of each substrate are also facing each other. Voltage is applied to each electrode such that an electric field is induced between the electrodes. Alignment of the liquid crystal molecules is changed by the varying intensity or direction of the electric field. The LCD device displays a picture by varying transmittance of the light according to the arrangement of the liquid crystal molecules.
An LCD device has pixels arranged in a matrix. An LCD device having a thin film transistor and a pixel electrode in each of the pixels is referred to as an active matrix LCD (AM-LCD) device. Such a device is widely used due to its high resolution and capacity to realize fast moving images.
In an LCD device, a pixel electrode can be formed on a lower substrate, which can be referred to as an array substrate, and a common electrode can be formed on an upper substrate, which can be referred to as a color filter substrate. Thus, an electric field induced between the pixel electrode and the common electrode is perpendicular to the substrates. Such an LCD device has high transmittance and a high aperture ratio. Further, breakdown of such an LCD device due to electrostatic discharge can be prevented because the common electrode functions as a ground.
FIG. 1 is an expanded perspective view illustrating the related art LCD device. The related art LCD device has a first substrate 22 and a second substrate 5, which are spaced apart from and facing each other, and also has a liquid crystal layer 14 interposed between the first substrate 22 and the second substrate 5. At least one gate line 13 and at least one data line 15 are formed on an inner surface of the first substrate 22 (i.e., the side facing the second substrate 5). The gate line 13 and the date line 15 cross each other and define a pixel region P.
A thin film transistor T is formed adjacent to each crossing of the gate line 13 and the data line 15. The thin film transistor T includes a gate electrode, a source electrode and a drain electrode. A pixel electrode 17, which is electrically connected to the thin film transistor T, is formed in the pixel region P on the first substrate 22. The pixel electrode 17 can be formed of a transparent conductive material, such as indium-tin-oxide (ITO), that transmits light relatively well. A plurality of such thin film transistors is arranged in a matrix form to correspond to other crossings of gate and data lines. The first substrate 22, which includes the thin film transistor T and the pixel electrode 17, is typically referred to as an array substrate.
A black matrix 6 is formed on an inner surface of the second substrate 5. The black matrix 6 has an opening that corresponds to the pixel electrode 17. A color filter layer 7 is formed in the opening of the black matrix 6. The color filter layer 7 includes three color filters 7a, 7b and 7c of red(R), green(G) and blue(B), which are sequentially arranged, and each color filter corresponds to one pixel electrode 17. A common electrode 18 is formed on the color filter layer 7. The common electrode 18 can be formed of a transparent conductive material, such as indium-tin-oxide (ITO), that transmits light relatively well. The second substrate 5, which includes the color filter layer 7, is typically referred to as a color filter substrate.
The array substrate of the LCD device is manufactured by repeatedly performing processes of depositing a thin film and patterning the thin film through a photolithographic process using a mask, i.e., a mask process. The photolithography process includes the steps of cleaning, coating a photo-resist layer, exposing through a mask, developing the photo-resist layer, and etching. Therefore, fabricating time, costs, and failure can be decreased by reducing the number of the photolithography processes.